db2 zos backup times

We have a DB2 version 8 Z/OS database running. We have recently done a 12 month purge of data on this database. The backup times have not decreased (actually we have seen an increase).
When I look at the number of pages being backed up for one of te larger tablespace it has increased from 4,031,390 to 4,068,340.
The program is doing an actual delete because we have done select statements using the key of some records that were purged and the select does not find these records, so they have been deleted.
Any thoughts ????

When you backup, do you mean "image copy" or something else?
Anyway, after purging the data did you run REORG and RUNSTATS? If not,
please run these utilities and rebind your program.
HTH,
KT
==> ibm-mainframe-tips.blogspot.com

Yes, it copies all pages whether there is any data or not. That's why you
need to run REORG to free up space. That's the reason I asked if you are
using Image Copy or just saving the data output through QMF or some other
program.

Hello Joe,
They're right to REORG your table(s) after the purge in order to recoup space from the deleted data.
As a DB2/IMS DBA for ITS/Blue2 and Manage Healthcare System at BCBSFL, I assisted our applications team to automate the process via our scheduler and
run the PURGE job after the ImageCopy and before the Reorg jobs, depending on how you schedule the maintenance jobs.
Like what Tim K. stated, it's also a best practice to REBIND your application package after the RUNSTATS. Since health care apps references multiple tables, ensure that all related tables has ran the REORG/RUNSTATS before the bind. I set up a batch BIND job that will execute after the maintenance jobs.
If this is a websphere apps, there's no apps to be rebind.